Method of and apparatus for forming slugs for use in extrusion processes



Api'il 9, 1935. w. T. DAVIS AL METHOD 011 AND APPARATUS FOR FORMING SLUGS FOR USE IN EXTRUSION PROCESSES Filed Aug. 12, 1931 5 Sheets-Sheet 1 April 1935- w. T. p vls ETAL 1,996,905

METHOD OF AND APPARATUS FOR FORMING SLUGS FOR USE IN'EXTRUSION PROCESSES Filed Aug. 12, 1931 5 sheets-sneak 2 I o o 4 i O O I 15 13 14 E I k 21 J8 1.9 127 20 4 INVENT R April 9, 1935. w; T. DAVIS El AL METHOD OF AND APPARATUS FOR FORMING SLUGS FOR USE IN EXTRUS ION PROCESSES Filed Aug. 12, 1 5 Sheets-Sheet 3 iNVENTOR April 1935- I w. T. DAVIS El A L- 1,996,905

METHOD of AND APPARATUS FOR FORMING SLUGS FOR USE IN EXTRUSIQN PROCESSES Filed Aug. l2, 1931 5 Sheets-Sheet 4 Y H Cl 11 4 5 4. it 12 i Y p 3 w. T. DAVIS E.TAL I 1,996,905 I P 1 0R USE IN EXTRUS Patented Apr. 9, 1 935 UNETED- STATES PATENT OFFlCE METHOD OF AND APPARATUS FOR FORM DWG SLUGS FOR USE IN EXTRUSIOL PROCESSES Walter T. Davis and John A. McGinnis, Wheeling,

W. Va., assignors to Wheeling Stamping Company, Wheeling, W. Va., a corporation of West Virginia v Application August 12, 1931, Serial No. 556,412

9 Claims. (Cl. 29-33) "This invention relates broadly to the formadoes not do any particular harm because it is tion of articles, such as collapsible tubes, by exforced into a part of the tube where the metal is trusion processes, and more particularly to a relatively thick and not attenuated to the extent method and apparatus for the production of that it is in the walls of the tube. Since the dross nonferrous slugs or blanks from which such does not have the ductility or malleability of the 5 articles are extruded. pure metal it constitutes an impurity, and in the More particularly, the present invention is for thinner extruded walls of a collapsible tube it is an improvement on the method disclosed in our apt to produce imperfections, such as very minute prior Patent No. 1,646,854, dated October 25, pores or holes which render the tube imperfect. 10 1927, and assigned to t W ee g Sta ping While the practice of the invention disclosed 10 Company. v in Patent No. 1,646,854 results in a practical According to our Said p t. there is provided method of forming tubes, there is, for the reasons a rotary disc having n n l r eries of sepanoted above, some slight loss by reason of the rated pockets therein and this disc is rotated in presence of dross to a greater or lesser extent on a step-by-step fashion to bring the pockets beach blank,

neath a pou Valve w y molten metal o According to the present invention we contemthe type used for making collapsible tubes 18 plate trimming the top of each blank after it has Poured into the Dockets mold oavities- The solidified either to remove a complete skin of valves employed are measuring valves, so that metal f the top of each blank; remove 10 a predetermined amount of metal is poured into skin of metal from the highportion of the top of 20 each pocket or recess. -When this metal hardens each blank so that only dross is eithr it forms a circular slug or disc which is subse pletely removed or is removed from the fluently ejected fromthe mold The Slug or tion of th bl kwher it roduces tr uble' the disc thus formed may thereafter be then put subsequeni i of extiusign. l 9 I into an extrusion press such as that shown in I our Patent No. 1,646,854, or the Davis Patent No. Accord-mg to preferred t b of prafctm 1 515 d t d d th to r mg our invention, the mold cavities or recesses 383 an ex m e m 6 may manna are filled to overflowing with molten metal and a to form tube or like article It will be underthen after the metal has solidified the excess is ztood tcslhat any type of extrusion app l may out 01f and the resulting blanks have a clean top g f welbknown fact that molten metal of surface free of dross from every portion where the type used for making collapsible tubes such it fifi g z to cagse g mg as lead and tin readily accumulates dross. 0 Over 1 2;? i olund 1 Although considerable effort has been made in g z z N 23 22: e as I5 practicing the invention disclosed in Patent No. 2' t g P flg 1,646,854 to reduce the formation ofdross to a 115 ea m e n 056 m minimum, it nevertheless happens that each slug patent, under a valve at the bottom of the melting cast by this process has a thin film 01' dross over pot which is open an the tune that the mold its surface. When the metal cools in the molds, cavmes are fined to excess with the'surplus 1 hi h 5 around the outside of the i cfld i zls fir t. with the" continued cooling table- A fixed knife is Pflwided under which the of the metal f ther Shrinkage occurs, and since table passes and this knife cuts on all of the surthe metal is solidified at the edges of the blank P t the shrinkage occurs at thecentenso that prac- 1 The invention a be more clearly understood tically every blank which is molded has the exby o to the acwmpgnying drawings in 45 posed or top surface slightly dished toward the whifih I center t k, Figure 1 represents a top plan view of an ap- When the blank is extruded the extrusion 'paratus embodying our inv nti n and ca y s plunger pushes the metal at the center of the out 0111' method; i

the metal at the top solidifying on the top. of the 60 blank downwardly to form what is subsequently, ure 2 s a side v ion o t e apparatus the neck of a collapsible tube while the metal at Shown in Figure the edges of the blank is extruded upwardly Figure 3J5 a e cal sectionv t ough a portion around the sides of the plunger to form the thin 01 the machine in substantially the'plane 01 line walls of the collapsible'tube. Dross which ac- III-III of Figure 2; cumulates at the center of the blank orbutton Figure 4 is a detail view or the stripping de- 55 vice for pushing the completed blanks out of the apparatus;

Figure 5 is a detail view showing the relative position of the cutting knife and hold down finger;

Figure 6 is a top plan view of a slight modification in which a positive drive is provided for the slug ejecting wheel;

Figure 7 is a vertical transverse section through the arrangement shown in Figure 6;

Figure 8 is a detail view showing the cooled table over which the casting disc moves;

Figure 9 is a view similar to Figure 3 of a slightly modified arrangement showing a different type of cutter and showing the invention applied to a table of the structure shown in Patent No. 1,646,854; r

Figure 10 is a somewhat enlarged sectional View through a blank, as heretofore commonly formed in using a machine of the type shown in Patent No. 1,646,854;

Figure 11 is a similar view of the blank after it has been trimmed according to our present invention; and

Figure 12 is a detail view representing diagrammatically theextrusion plunger and the manner in which the blank is positioned under the die.

Referring first to Figure 10, it will be seen how the metal freezes when it is poured into the individual mold cavities of the machine as shown in Figure 5, the outer portion of the blank being higher than theextreme edges orthe central portion. In this figure the blank is designated A, and B designates the high portion, while 0' dtes the center portion which is dished downwardly from the'contraction of the metal upon solidifying from the outside toward the center. The top surface of the button A contains more or less dross, produced largely from the oxidation or the metal while it is cooling in the mold cavities.

According to the present invention, the button A is cast somewhat thicker than is required in the resulting blank. Theexcess metal above the line D-D istrimmed off. All of the top of the button may be removed so that the button is flat across the top, or, as shown in Figure 11, it may be trimmed so that all of the portion B is removed and only alvery small part :ofthe original skin is left at C. .The presence of a small amount of dross at C is not objectionable for the reason that when the slug or blank A is put in the customary extruding die E shown in Figure .12 and subjected to pressureby the extruding plunger F the metal at the center of the blank, including the original skin at C, is forced downwardly into that part of the mold which forms thehead of the collapsible tube, while it is the metal to the sides of the central portionC that is extruded upwardly around the plunger F-to form the thin walls of the collapsible tube.

,As previously stated, our invention contemplates either the complete removal of the top skin of theblank, or the removal of most of the top portion of the blank except the small area at C.

In Figures 1' to 5, inclusive, we have shown a preferred embodiment of an-apparatus for practicing our invention. The machine as. shown comprises a supporting structure or frame 2 above the top of which'is supported a casting table 3 which is in the form of a ring having a cut-out portion 4 therein, as shown'in Figure '4. Below this table is a water chamber 5 through which water may be circulated for cooling the table 3. To provide for this circulation of waterthere are water- I shown Figure 1 an inlet pipe 6 and a discharge pipe 1. Setting on the table 3 is a circular disc 8 having an annular series of holes or recesses 9 extending through it. The top of the table may a be conveniently formed with a shallow channel or,groove III, with the casting recesses 9 formed in the bottom of this channel or groove. The disc wheel l3 which engages a worm H on a drive -8 is secured to a base plate II on a vertical shaft l2. On the lower end of the shaft I2 is a worm shaft IS. The drive shaft l 5 may be conveniently Leading from the bottom of this tank is a discharge pipe 23 having a valve 24 thereinand a' discharge spout 25, this discharge "spout overhanging the casting table 3 and the casting disc 8 so as to discharge metal into the holes or recesses 9. The valve 24 may be adjusted to regulate the how of metal therethrough in order that the flow of metal will be properly proportioned to the speed of rotation of the disc 8 and the number and sizeof therecesses 9. I

making collapsible tubes is melted and stored.--

In the operation of the machine the disc 8 is continuously rotatedandmetal pours continuously from the discharge spout 25 into the holes in the casting disc, filling them to overflowing and the excess metal freezes in the groove or channel III. In Figure 1 the appearance of the filled recesses with thecontinuwsirregular strip of excess metal in the groove III is shown, the excess metal having sinuous edges as shown.

Positioned over the casting disc 8 opposite the pouring spout 25- is a fixed bracket 26 on which is carried an inclined knife 21, this knife being sloped toward the rotating table andthe cutting edge 28 of the knife bears in the groove III, the

cutting edge of the knife riding on the bottom ofthegroove Ill. 'Ihisisbests'howninFigurel For convenience the knife 21 is made removable.

and adjustable as indicated.

Assuming the casting disc 8 to be rotating in an anti-clockwise direction, as indicated by the arrow in Figure 1, the excess metal is cut away from the buttons of metal in the casting re cesses Qfithis excess metal coming off in the form of a continuous shaving or strip 29 as indicated in Figures 1 and 2. A chute 30 is provided for the shavings of excess metal to fall upon and be guided into a bucket in which they may be collected to be subsequently re-meltedQ In order to make the action of the cutter more effective and to keep the excess metal fromlifting the button-like blanks out of the recesses 9, a pressure finger 3| is provided which bears against the top of the metal just in advance of the cutter,

pockets 9 individual detached buttons ofmetal,

onebuttonbeingprovidedineachrecess. A!

the dross that forms in .the process of casting collects as a skin on the excess metal which is cut awayso that each button is entirely clean on the top. Under some conditions there may be a lesser thickness of excess metal to be removed. in which case the buttons, instead of. having the entire top surface cut away, would have only the high part of the top surface cut away, as explained in the first part of this specification in connection with Figs. 10 and 11.

, For ejecting the buttons or slugs from the recesses 9 we "have shown a sprocket wheel 34 ca :ied on a bracket 35 positioned over the cutaway portion 4 of the casting table I. The teeth of the sprocket wheel are spaced to enter the holes 9 and are of sufficient length toproject into the holes 9 and push the slugs or buttons of metal, designated 36, out oi their recesses, as clearly shown in Fig. 4, into a chute 38. The rotation of the casting ring 8 may be conveniently utilized to operate this toothed wheel, the disc 8 with its holes 9 serving as a driving gear.

It has been found, however, thatwhere the toothed wheel is driven directly by engagement with the holes or recesses in the casting disc, as described, it tends to wear the edges of the mold cavities and to slightly mark the metal slugs. A

simple way of avoiding this difiiculty is to positively drive the ejecting wheel 34 by an arrangement such as that shown in' Figures 6 and 7.

the method of operation at once becomes clearly apparent. The metal flows continuously into the pockets of the continuously revolving casting disc" .8; the freezing or solidification of the metal is faccelerated by th circulation of water under the table I; and afte the metal has solidified the excess is shaved oi! the top and the individual buttons, free or substantially free of dross are ejected from the holes 9, falling onto the chute. These buttons may then be lubricated as is the usuaLpractice, and subjected to the usual process of extrusion. Extrusion apparatus is shown in our prior Patent No. 1,646,854 and in the Davis Patent No. 1,515,383, Any such apparatus may be used. By reason of the fact that the dross is removed from either the'entire top surface of the button or from that portion of the surface where it is objectionable, the loss by the formation of imperfect tubes due to the presence of dross is very considerably c The machine has a considerable advantage over machines of the type disclosed in our priorPatent No. 1,643,854 in that the isno intermittent valve operation and no intermittent. movement of the casting disc. Since the casting disc rotates continuously in the present machine; the valve redisclosed in the prior patent, having casting recesses ll therein with an ejector 42 in the bottom of each recess. The tops may be shaved off the blanks by the use of a knife as shown in Figure 1, or a continuously driven rotary cutter .3, as shown in Figure 9. may be used. This cutter bears against the top of the table and is continuously rotated through a shaft 44. The knives of the cutter moving across the tops of the blanks serve to remove the excess metal. The amount of excess metal removed is determined by the amount of excess metal which is poured into the mold. In view of the much speedier operation of the machine shown in Figures 1 to 8, inclusive, over a machine of the intermittent table type as shown in Figure 9, we obviously prefer to use the continuously moving casting ring type.

Since the excess metal which is sha -(ed of! in the practice of our invention is collected and can be dumped back into the melting pot and used over again, there is no appreciable loss of metal arising from the fact that the molds are filled to excess instead of being filled with the exact weight of metal necessary to form a tube, and the excess then shaved oil. Because of the improved quality of the blanks due to the removal of the dross, from that portion whereit causes trouble,

and due to the fact that the molds can be moved continuously instead of intermittently, the present invention offers considerable advantage over the formation of theseslugs by previous methods.

While we have shown and described certain specific embodiments of our invention, it will be I understood that various changes and modifications may be made therein. It will also be understood that a fixed knife may be used in place of the rotary cutter in Figure 9, or that a rotary cutter as shown in Figure 9 can be adapted for use with the apparatus shown in Figures 1 to 8, as it is not material how the excess metal is removed.

We claim:

1. A slug casting machine of the class described comprising a, rotary carrier having a series of mold cavities therein, a pouring spout for dischargingmetal into the mold cavities, means for rotating the carrier, a. cutter comprising an inclined knife bearing against the top of the carrier for shaving off excess metal fromthe slugs cast in the mold cavities and removing excess metal from the top of the carrier, and a pressure finger over the carrier located slightly in advance of the knife and cooperating therewith for'keeping the knife *from lifting the slugs out of the mold cavities.

2. A slug casting machine of the class described comprising a rotary carrier having a series of mold cavities therein, a pouring spout for discharging in'etal into the mold cavities, means for rotating the carrier, a cutter comprising an inclined' knife bearing againsttl ie top of the carrier for shaving off excess metal from the slugs cast in the mold cavities and removing excess metal ,from the top of the carrier, a pressure finger over the carrier located slightly in advance of the knife and cooperating therewith for keeping the knife from lifting the slugs out of the mold cavities,

the mold cavities in said carrier comprising holes passing completely therethrough, and a table over which the carriermoves for closing the bottoms of the holes, the holes being slightly larger it the bottom'than at the top for also resisting the tendency of the knife to lift the slugs out of the mold.

3. A';slug casting machine of the class described comprising a'rotary carrier having a series of mold cavities therein, a pouring spout for discharging metal into the mold cavities, means for rotating the carrier, a cutter comprising an inclined knife bearing against the top of the carrier for shaving ofi excess metal from the slugs cast in the mold'cavities and removing excess metal from the top of the carrier, a pressure finger over the carrier located slightly in advance of the knife and cooperating therewith for keeping .the knife from lifting the slugs out of the mold cavities, .the mold cavities in said carrier comprising hole'spassing completely therethrough, a

table over which the carrier moves for closing the bottoms of theholes, the holes beingslightly larger at the bottom than at the top for also resisting the tendency of the knife to lift the slugs-out of the mold, said table having a cut-away portion between the knife and the pouring spout so arranged that when the niold cavities move over the cut-away portion the slugs therein are unsupported at the bottom, and means locatedover the carrier for. pushing the slugs out of the mold cavities'through this cut-away 'portion of the table. Y Y

4. A method of reducing the occurrence of imperfections such as pinholes in containers extruded fromcast blanks, which-includes the steps of molding the blanks and during the molding pouring suiiicient metalabove the mold to provide metal at the top. of the mold substantially free ofdross and removing the surface of the blank to extrusion to form a container.

7. In a method of avoiding imperfections such as pinholes in containers extruded. from a cast blank, the steps including delivering molten metal to a moving blank mold and during the molding pouring sumcient metal above the mold to provide.

metal at the top of the mold substantially'free of dross, progressively removing the surface of the blank which cools out of contact with the walls of the mold, while the body of the blank remains in the mold and continues to move, and electing the blank from the mold.

8. The method defined by claim 7 wherein the blank is extruded to form a container.

9. In a method of eliminating imperfections from the walls of vcontainers extruded from a cast.

blank, the steps including pouring molten 'inetal into a mold and until themold is slightly overi filled and to a suillcient amount to provide metal above the mold-substantially free of dross, removing the excess material after the blank has cooled, electing the blank from the mold, and extruding it into the form of a container.

. WALTER 'r; DAVIS.

JOHN A. McGINNIS. 

